This research program involves the study of physiological processing associated with auditory detection using an awake-and- behaving Rabat preparation. This research is a continuation of efforts that have focused on neural mechanisms, such as covergence and coincidence detection, that are hypothesized to play a role in the encoding and processing of complex sounds, especially in the presence of noise. In the sequence of studies proposed here, the relationship between neural processing and the psychophysical performance of an animal will be determined. Single-unit recordings will be made from auditory neurons in an animal during a detection task based upon the classically conditioned eyeblink response. Initial effort will focus on recording in the inferior colliculus (IC). The binarural masking level difference (BMLD), a robust binaural detection phenomenon, provides a paradigm in which the animal's performance on the detection task can be studied while systematically varying important binaural cues that have been demonstrated to influence both the BMLD and the responses of cells in the IC. These experiments will yield new information related to models for detection of signals in noise, and in particular, for the binaural detection problem. The long-term goal of this work is the development of improved signal-processing strategies for aiding detection and discrimination of signals in noise for persons with hearing loss. In addition, this work represents the development of a robust preparation that allows chronic neurophysiological study of awake and attentive subjects; this approach has been of fundamental importance in other fields of neuroscience, such as vision, somatosensation, motor control, and learning. Auditory neuroscientists have not taken full advantage of this combined approach to the study of neurophysiology and behavior.